An improved microfluidic device to enhance the enrichment factors in liquid phase microextraction: application to the simultaneous extraction of polar and non-polar acids in biological samples.

A new microfluidic device to enhance the enrichment factor in miniaturized systems is proposed. The microfluidic system was design for liquid phase microextractions, and it was applied to the simultaneous extraction of acidic compounds of a wide range of polarity (0.5 < log P < 3). The device operated under stagnant acceptor phase conditions and all the operational parameters involved were optimized. Tributyl phosphate was found to be a new highly efficient supported liquid membrane to simultaneously extract analytes of very different polarities. The optimal donor and acceptor phase were pH 2 and pH 13, respectively. The donor flow rate and the extraction time were investigated simultaneously, offering great versatility with high enrichment factors (EFs). Limits of quantitation were within 0.02 and 0.09 µg mL-1 for all compounds at 10 µL min-1 as donor flow rate and 20-min extractions, offering EFs between 11 and 18 with only 200-µL sample volume consumption. The method was successfully applied to human urine samples, observing recoveries between 47 and 90% for all compounds. This new proposed microfluidic system increases the wide range of applications, especially when the analytes are present in lower concentrations in the sample.

Bioaccumulation and biochemical responses in the peppery furrow shell Scrobicularia plana exposed to a pharmaceutical cocktail at sub-lethal concentrations.

Pharmaceutical drugs in the aquatic medium may pose significant risk to non-target organisms. In this study, the potential toxicity of a mixture of three compounds commonly detected in marine waters (ibuprofen, ciprofloxacin and flumequine) was assessed, by studying bioaccumulation, oxidative stress and neurotoxicity parameters (catalase CAT, superoxide dismutase SOD, glutathione reductase GR, glutathione S-transferase GST, lipid peroxidation LPO, glutathione peroxidase GPX, metallothionein MT and acetylcholinesterase AChE) in the clam Scrobicularia plana. Temporal evolution of selected endpoints was evaluated throughout an exposure period (1, 7 and 21 days) followed by a depuration phase. The accumulation of all drugs was fast, however clams showed the ability to control the internal content of drugs, keeping their concentration constant throughout the exposure and reducing their content after 7 days of depuration. The induction of biochemical alterations (SOD, CAT, LPO, MT, AChE) was observed in gills and digestive gland probably related to an imbalance in the redox state of clams as a consequence of the exposure to the drug mixture. These alterations were also maintained at the end of the depuration week when the high levels of SOD, CAT, GST and LPO indicated the persistence of oxidative stress and damage to lipids despite the fact that clams were no longer exposed to the mixture.

Assessment of pharmaceutical mixture (ibuprofen, ciprofloxacin and flumequine) effects to the crayfish Procambarus clarkii: A multilevel analysis (biochemical, transcriptional and proteomic approaches).

The knowledge about the effects of pharmaceuticals on aquatic organisms has been increasing in the last decade. However, due to the variety of compounds presents in the aquatic medium, exposure scenarios and exposed organisms, there are still many gaps in the knowledge on how mixtures of such bioactive compounds affect exposed non target organisms. The crayfish Procambarus clarkii was used to analyze the toxicity effects of mixtures of ciprofloxacin, flumequine and ibuprofen at low and high concentrations (10 and 100 µg/L) over 21 days of exposure and to assess the recovery capacity of the organism after a depuration phase following exposure during additional 7 days in clean water. The crayfish accumulated the three compounds throughout the entire exposure in the hepatopancreas. The exposure to the mixture altered the abundance of proteins associated with different cells functions such as biotransformation and detoxification processes (i.e. catalase and glutathione transferase), carbohydrate metabolism and immune responses. Additionally changes in expression of genes encoding antioxidant enzymes and in activity of the corresponding enzymes (i.e. superoxide dismutase, glutathione peroxidase and glutathione transferase) were reported. Alterations at different levels of biological organization did not run in parallel under all circumstances and can be related to changes in the redox status of the target tissue. No differences were observed between control and exposed organisms for most of selected endpoints after a week of depuration, indicating that exposure to the drug mixture did not produce permanent damage in the hepatopancreas of P. clarkii.

Monitoring of pharmaceuticals in aquatic biota (Procambarus clarkii) of the Doñana National Park (Spain).

In this work the presence of different pharmaceuticals at Doñana National Park (Spain) and their main entry sources (input source or entry points) have been stated over the 2011-2016 years period. Twenty-three selected pharmaceuticals (corresponding to eight therapeutic families) were evaluated in crayfish and water samples from Doñana National Park (Spain) (six sampling points selected in order to cover different possible pollution sources into and surrounding the Park). The multiresidue determination was carried out using enzymatic-microwave assisted extraction prior to high performance liquid chromatography mass spectrometry detection. Sulphonamides (sulfadiazine, sulfamerazine, sulfamethazine, and sulfamethoxazole); trimethoprim, an antibiotic that is frequently co-administered with sulfamethoxazole; amphenicols (chloramphenicol, florfenicol and thiamphenicol); fluoroquinolones (ciprofloxacin, enrofloxacin, flumequine, danofloxacin, gatifloxacin, norfloxacin, marbofloxacin and grepafloxacin); penicillins (amoxicillin); tetracyclines (chlortetracycline and oxytetracycline); non-steroidal anti-inflammatory drugs (salicylic acid and ibuprofen); beta-blocker drugs (atenolol); and antiepileptics (carbamazepine) were analysed. Ciprofloxacin, ibuprofen, salicylic acid, flumequine, and carbamazepine were detected and/or quantified at some of the selected sampling points. A clear ecotoxicological risk to the ecosystem was demonstrated from the occurrence of ciprofloxacin in samples obtained after the punctual and massive presence of people inside the Park. Furthermore, flumequine and carbamazepine have been detected in Procambarus clarkii specimens in concentrations around 30 ng g-1 and 14 ng g-1, respectively, and their occurrence in the specimens could indicate the persistence of the discharge sources. The main source of pharmaceuticals into the Park might be the livestock farming activities, and the influence of urban wastewaters from surrounding villages does not seem to be very important.

Direct capillary electrophoresis analysis of basic and acidic drugs from microliter volume of human body fluids after liquid-phase microextraction through nano-fibrous membrane.

In the present work, a disposable microextraction device with a polyamide 6 nano-fibrous supported liquid membrane (SLM) is employed for the pretreatment of minute volumes of biological fluids. The device is placed in a sample vial for an at-line coupling to a commercial capillary electrophoresis instrument with UV-Vis detection (CE-UV) and injections are performed fully automatically from the free acceptor solution above the SLM with no contact between the capillary and the membrane. Up to 4-fold enrichment of model basic (nortriptyline, haloperidol, loperamide, and papaverine) and acidic (ibuprofen, naproxen, ketoprofen, and diclofenac) drugs is achieved by optimizing the ratio of the donor to the acceptor solution volumes (16 to 4 µL, respectively). The actual setup enables SLM extractions from less than a drop of sample and is suitable for pretreatment of scarce human body fluids. Two unique methods are reported for efficient clean-up and enrichment of the basic and acidic drugs from capillary blood (formed as dried blood spot), serum, and urine samples, which enable their determination at therapeutic and/or toxic levels. The hyphenation of the SLM extraction with CE-UV analysis provides good repeatability (RSD, 2.4-14.9%), linearity (r2, 0.988-1.000), sensitivity (LOD, 0.017-0.22 mg L-1), and extraction recovery (ER, 20-106%) at short extraction times (10 min) and with minimum consumption of samples and reagents. Graphical abstract.

A New Microchip Design. A Versatile Combination of Electromembrane Extraction and Liquid-Phase Microextraction in a Single Chip Device.

For the first time, a novel and versatile microfluidic device was developed to achieve the possibility of combining different extraction principles using a miniaturized approach for the extraction of different classes of analytes. This novel microchip is composed of a sandwich of three poly(methyl methacrylate) (PMMA) layers. Four channels allowed the combination of electromembrane extraction (EME) and liquid-phase microextraction (LPME) in three different ways: (I) EME and LPME, (II) EME and EME, or (III) LPME and LPME. The microchip can be used either (a) using a common acceptor phase (for both extractions) for the simultaneous extraction of drugs from different nature in a single step, or (b) a common sample solution (for both extractions) and two acceptor solutions for simultaneous drug separation. In this work, the performance of this novel microchip was demonstrated by simultaneous integration of EME and LPME using a common acceptor phase for both extractions. This configuration reduces the time of analysis allowing direct analysis in a single chip. The microchip was tested for extracting two different classes of analytes: five fluoroquinolones and four parabens as model analytes. All effective variables were optimized for EME and LPME. Under the optimized conditions, the reusable microchip enables simultaneous µ-EME/LPME with extraction efficiencies over 77% in only 8 min extraction and sample volume consumption lower than 40 µL. The optimized procedure was successfully applied to urine samples obtaining recoveries over 90% for all analytes.

Recent trends in capillary electrophoresis for complex samples analysis: A review.

CE has been a continuously evolving analytical methodology since its first introduction in the 1980s of the last century. The development of new CE separation procedures, the coupling of these systems to more sensitive and versatile detection systems, and the advances in miniaturization technology have allowed the application of CE to the resolution of new and complex analytical problems, overcoming the traditional disadvantages associated with this method. In the present work, different recent trends in CE and their application to the determination of high complexity samples (as biological fluids, individual cells, etc.) will be reviewed: capillary modification by different types of coatings, microfluidic CE, and online microextraction CE. The main advantages and disadvantages of the different proposed approaches will be discussed with examples of most recent applications.

Electromembrane extraction for the determination of parabens in water samples.

To our knowledge, for the first time an electromembrane extraction combined with a high-performance liquid chromatography procedure using diode-array detection has been developed for the determination of five of the most widely used parabens: ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, butyl 4-hydroxybenzoate, isobutyl 4-hydroxybenzoate, and benzyl 4-hydroxybenzoate. Parabens were extracted from pH 4 aqueous sample solutions with use of an Accurel® S6/2 polypropylene hollow fiber that supports a liquid membrane of 1-octanol to a pH 12 aqueous acceptor solution placed inside the lumen of the hollow fiber. An electric current of 30 V was applied over the supported liquid membrane by means of platinum wires placed in the donor and acceptor phases. Parabens were extracted in 40 min with enrichment factors in the 30-49 range. The procedure has detection limits between 0.98 and 1.43 µg L(-1). The method was applied to the determination of parabens in surface environmental waters with excellent results.

Agar films containing silver nanoparticles as new supports for electromembrane extraction.

A new support containing silver nanoparticles to assist electromembrane extraction (EME) procedures is proposed. For the first time, synthesized agar films containing silver nanoparticles (AgNPs) have been used as a support for liquid membranes in EME. Agarose films of 20 µm thickness containing 107.9 mg Ag/g agar were synthesized and characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM), showing isolated spherical silver nanoparticles of 20-30 nm diameter with homogeneous distribution. Nanometallic films were cut and glued to narrow bore glass tubes and used as supports for a dihexyl ether liquid membrane for use in an EME procedure. EME conditions were optimized and applied to the extraction of selected non-steroidal anti-inflammatory drugs (NSAIDs). The results were compared to those using polypropylene membranes (450 µm and 100 µm thickness), achieving 10- to 70-fold higher extraction efficiency. This article opens a new line of research into electrically assisted microextraction systems by combining other possible kinds of nanometallic films, including different metals, film functionalization through metallic NPs, and the use of low polarity solvents. Also, very low currents are obtained during the extraction process, which lead to high electromigration of the analytes.

Hollow-fiber liquid-phase microextraction for the direct determination of flumequine in urban wastewaters by flow-injection analysis with terbium-sensitized chemiluminescence.

A flow-injection analysis chemiluminescence method based on the enhancement effect of the flumequine-Tb(III) complex on the weak native emission of the Ce(IV)-Na2SO3 system has been developed for the determination of flumequine. The method includes a cleanup and preconcentration stage (750-fold) of the sample by hollow-fiber liquid-phase microextraction using an Accurel(®) Q 3/2 polypropylene hollow fiber impregnated with 1-octanol as the supported liquid membrane. The obtained 50 µL acceptor phase was injected in a 1 mM Tb(III) + 4 mM Ce(IV) in 5% v/v H2 SO4 stream and mixed with a 2 mM Na2 SO3 stream before its introduction into the flow cell. The chemiluminescence signal was linear in the 0.3-15 ng/mL range, with detection and quantitation limits of 0.1 and 0.3 ng/mL, respectively. The method allows the selective extraction and determination of flumequine in wastewater samples, using simpler and lower-cost instrumentation and with shorter extraction and analysis times than traditional high-performance liquid chromatography analysis.

Bioavailability of flumequine and diclofenac in mice exposed to a metal-drug chemical cocktail. Evaluation of the protective role of selenium.

BACKGROUND AND PURPOSE: Organisms, including humans, are subjected to the simultaneous action of a wide variety of pollutants, the effects of which should not be considered in isolation, as many synergies and antagonisms have been found between many of them. Therefore, this work proposes an in vivo study to evaluate the effect of certain metal contaminants on the bioavailability and metabolism of pharmacologically active compounds. Because the most frequent entry vector is through ingestion, the influence of the gut microbiota and the possible protective effects of selenium has been additionally evaluated. EXPERIMENTAL APPROACH: A controlled exposure experiment in mammals (Mus musculus) to a "chemical cocktail" consisting of metals and pharmaceuticals (diclofenac and flumequine). The presence of selenium has also been evaluated as an antagonist. Mouse plasma samples were measured by UPLC-QTOF. A targeted search of 48 metabolites was also performed. KEY RESULTS: Metals significantly affected the FMQ plasma levels when the gut microbiota was depleted. Hydroxy FMQ decreased if metals were present. Selenium minimized this decrease. The 3-hydroxy DCF metabolite was not found in any case. Changes in some metabolic pathways are discussed. CONCLUSIONS AND IMPLICATIONS: The presence of metals in the mouse diet as well as the prior treatment of mice with an antibiotic mixture (Abxs), which deplete the gut microbiota, has a decisive effect on the bioavailability and metabolism of the tested pharmaceuticals and dietary selenium minimize some of their effects.

Electromembrane extraction (EME)--an easy, novel and rapid extraction procedure for the HPLC determination of fluoroquinolones in wastewater samples.

For the first time, an electromembrane extraction combined with a HPLC procedure using diode array and fluorescence detection has been developed for the determination of seven widely used fluoroquinolones (FQs): marbofloxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, gatifloxacin and grepafloxacin. The drugs were extracted from acid aqueous sample solutions (pH 5), through a supported liquid membrane consisting of 1-octanol impregnated in the walls of a S6/2 Accurel® polypropylene hollow fiber, to an acid (pH 2) aqueous acceptor solution inside the lumen of the hollow fiber. The main operational parameters were optimized, and extractions were carried out in 15 min using a potential of 50 V. Enrichment factors of 40-85 have been obtained using only 15 min of extraction time versus 330 min used in a previously proposed hollow-fiber liquid-phase microextraction procedure. The procedure allows low detection and quantitation limits of 0.005-0.07 and 0.007-0.15 µg L(-1), respectively. The proposed method was successfully applied to the FQs analysis in urban wastewaters.

Uptake study in Juncus sp. and Salicornia europaea of six pharmaceuticals by liquid chromatography quadrupole time-of-flight mass spectrometry.

In this work, eight plants of Juncus sp. and ten of Salicornia europaea were used for an uptake assay of pharmaceuticals (flumequine, cirpofloxacin, enrofloxacin, carbamazepine, diclofenac and ibuprofen) by irrigation at three concentration levels: 10 ng mL-1 (low level); 700 ng mL-1 (medium level) and 10 µg mL-1 (high level). Two plants irrigated with pharmaceutical-free water were set up as controls. For each level, two plants were watered every day with 50 mL (Juncus sp.) and every two days with 20 mL (Salicornia europaea) of aqueous solutions containing all the analytes at the described concentrations. Plants irrigated at 10 µg mL-1 were significantly the most affected, whereas the rest of the plants remained, in general, largely displayed no apparent physiological effects throughout the 30 days (Juncus sp.) and 21 days (Salicornia europaea) assays. Leaves and stems were cut every seven days and roots were collected at the end of the assay. The samples were lyophilized, submitted to a microwave assisted extraction using 5 mL of acetonitrile:water mixture (1:1, v/v) and they were analyzed (in triplicate) in a liquid chromatography-quadrupole time of flight mass spectrometry instrument. Most of the analytes were quantified in many of the samples corresponding to the three exposure levels with the highest concentrations obtained at high exposure levels. Ibuprofen was not detected in any sample and enrofloxacin, ciprofloxacin and diclofenac were not detected in the samples from Salicornia europaea.

A Method for the Determination of Veterinary Drugs from Different Therapeutic Classes in Animal Urine.

A rapid, precise and robust HPLC separation procedure has been developed and optimized for the determination of a series of drugs of different therapeutic classes: chlortetracycline, oxitetracycline, cefoperazone, diclofenac, tiamphenicol, marbofloxacin, ciprofloxacin, danofloxacin, enrofloxacin and flumequine. The chromatographic method used a monolithic C18 column and both diode array and fluorescence detection. This procedure was validated for the analysis of drugs in cow urine, using a simple and fast procedure with methanol/acetonitrile, allowing the simultaneous and efficient extraction of most of the studied drugs. The proposed method was successfully applied to the determination of enrofloxacin in cow urine, collected after the administration of this antibiotic.

Chitosan tailor-made membranes as biopolymeric support for electromembrane extraction.

A chitosan membrane composed by 60% (w/w) chitosan and 40% (w/w) Aliquat®336 has been proposed as a new biopolymeric support for electromembrane extraction. The new support has been characterized by Scanning Electron Microscopy, resulting a 30-35 µm thickness. Amoxicillin, nicotinic acid, hippuric acid, salicylic acid, anthranilic acid, ketoprofen, naproxen and ibuprofen have been successfully extracted using the proposed support. Better enrichment factors were obtained for the acidic polar analytes than for the non-steroidal anti-inflammatory compounds (ranging from 118 for hippuric acid and 20 for ibuprofen). Electromembrane extraction was developed applying a DC voltage of 100 V, 1-octanol as supported liquid membrane and 20 min of extraction. The target analytes have also been satisfactorily extracted from human urine samples, providing high extraction efficiencies. The chitosan membrane is presented as a promising alternative for supporting liquid membrane compared to commonly used materials for this purpose.

Quick Analysis of Organic Amendments via Portable X-ray Fluorescence Spectrometry.

The determination of heavy metals in soils and organic amendments, such as compost, manure, biofertilizer, and sludge, generally involves the digestion of samples with aqua regia, and the determination of those in the solution using various techniques. Portable X-ray fluorescence (PXRF) has many advantages in relation to traditional analytical techniques. However, PXRF determines the total elemental content and, until now, its use for the analysis of organic amendments has been limited. The objective of this work is the calibration of a PXRF instrument to determine the aqua regia-soluble elemental contents directly in solid samples of organic amendments. Our proposal will avoid the digestion step and the use of other laboratory techniques. Using a training set of samples, calibration functions were obtained that allow the determination of the aqua regia-soluble contents from the PXRF readings of total contents. The calibration functions (obtained by multiple linear regression) allowed the quantitative determination of the aqua regia-soluble contents of Fe, K, P, S, Zn, Cu, Pb, Sr, Cr, and Mn, as well as the organic matter content and a semi-quantitative assessment of Al, Ca, V, Ba, Ni, and As contents. The readings of Si, Fe, Al, Ca, K, or S were used as correction factors, indicating that the calibrations functions found are truly based on the chemical composition of the sample matrix. This study will allow a fast, cheap, and reliable field analysis of organic amendments and of other biomass-based materials.

Simultaneous determination of metformin and glimepiride in human serum by ultra high performance liquid chromatography quadrupole time of flight mass spectrometry detection.

This work proposes a simple method for the simultaneous determination of two antidiabetic compounds, metformin and glimepiride, by ultra-high performance liquid chromatography using quadrupole time of flight mass spectrometry detection with electrospray ionization. The method was validated and shown to be linear, selective, accurate and precise. The chromatographic separation was performed using a BEH C18 column (50 mm x 2.1 mm, 1.7 µm particle size). The mobile phase was composed by 0.05% (v/v) aqueous formic acid solution and acetonitrile using a gradient elution program, at a flow rate of 0.3 mL/min. Linearity range for metformin was 1.7-100 µg·L-1, using propranolol as internal standard and 3.3-100 µg·L-1 for glimepiride using glibenclamide as internal standard. Limits of detection and lower limits of quantitation were 0.4 µg·L-1 and 1.7 µg·L-1 for metformin and 0.7 and 3.3 µg·L-1 for glimepiride, respectively. The method was used for the simultaneous determination of these compounds in human serum samples with lower limits of detection and quantitation than serum levels reported in previous works that allows its applicability in therapy drug monitoring.

Multiresidue determination of 21 pharmaceuticals in crayfish (Procambarus clarkii) using enzymatic microwave-assisted liquid extraction and ultrahigh-performance liquid chromatography-triple quadrupole mass spectrometry analysis.

In this paper, a multiresidue enzymatic-microwave assisted extraction prior to ultrahigh performance liquid chromatography and triple quadrupole mass spectrometry analysis has been developed for the determination of 21 pharmaceuticals in crayfish (Procambarus Clarkii) samples. The analysed compounds corresponding to 6 therapeutic families were: fluoroquinolones (ciprofloxacin, danofloxacin, enrofloxacin, flumequine, gatifloxacin, grepafloxacin, marbofloxacin and norfloxacin); tetracyclines (chlortetracycline and oxytetracycline); sulphonamides (sulfamethoxazole, sulfadiazine, sulfamethazine, sulfamerazine); penicillins (amoxicillin); anfenicols (chloramphenicol, thiamphenicol and florfenicol); non-steroidal anti-inflammatory drugs (ibuprofen and salicylic acid) and trimethoprim an antibiotic that is frequently co-administered with sulfamethoxazole. The main factors affecting the extraction efficiency were optimized for 0.5 g of lyophilized tissue. The enzymatic microwave extraction was carried out using an extraction time of 5 min with 5 mL of an acetonitrile: water (1:1, v/v) mixture, 50 µL of Proteinase-K solution and 5 µL of formic acid at 50 W. After centrifugation, the liquid extract was evaporated and the residue was reconstituted with 1 mL of 0.1% (v/v) formic acid. Chromatographic and MS parameters, in both positive and negative ionization modes, were also optimized. The mobile phase used consisted on a mixture of 0.1% (v/v) formic acid aqueous solution and acetonitrile in gradient elution mode at a 0.4 mL min-1 flow rate. The proposed method was validated and recoveries over 70% were obtained for all the analytes with detection limits in the 0.6-12 ng g-1 range. The proposed method was successfully applied to crayfish specimens from Doñana National Park, Spain.

Liquid chromatography quadrupole time-of-flight mass spectrometry determination of six pharmaceuticals in vegetal biota. Uptake study in Lavandula dentata.

A procedure based on microwave assisted extraction for the determination of 6 pharmaceuticals in samples of Lavandula dentata, Salicornia ramosissima and Juncus sp. by liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOF/MS) was optimized and validated. Best results were obtained using microwave assisted extraction of 1.0g of homogeneous lyophilized samples and 5mL of a mixture ACN:H2O (1:1 v/v) as extracting solvent. Analytical recoveries ranged from 60 to 107% with relative standard deviation (RSD) lower than 15%. Limits of quantitation (LOQ) for the 6 pharmaceuticals flumequine (FLM), carbamazepine (CBZ), ciprofloxacin (CPR), enrofloxacin (ENR), diclofenac (DCL), and ibuprofen (IBU) were in the range 20.8-125ngg-1. The method was satisfactory applied for an uptake study in Lavandula dentata samples finding quantifying concentrations of FLM and CBZ in roots, leaf and stem.

New nanostructured support for carrier-mediated electromembrane extraction of high polar compounds.

A new support has been proposed to be used for carrier-mediated electromembrane extraction purposes. The new support (Tiss®-OH) is a 100µm thickness sheet nanofiber membrane manufactured by electrospinning and composed by acrylic nanofibers. It has been used in an electromembrane extraction (EME) combined with a HPLC procedure using diode array detection. The proposed method has been used for the extraction of four high polarity acidic compounds: nicotinic acid, amoxicillin, hippuric acid and salicylic acid. Analytes were extracted from an aqueous sample solution (pH 4) (donor phase) using a Tiss®-OH sheet that supports a 5% (w/v) Aliquat®336 in 1-octanol liquid membrane. Aqueous solution (pH 6) was used as acceptor phase. The electrical field was generated from a d.c. electrical current of 100V through two spiral shaped platinum wires placed into donor and acceptor phases. Analytes were extracted in 10min with recoveries in the 60-85% range. The proposed EME procedure has been successfully applied to the determination of the target analytes in human urine samples.